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  2. Planck units - Wikipedia

    en.wikipedia.org/wiki/Planck_units

    Some authors define the base Planck units to be those of mass, length and time, regarding an additional unit for temperature to be redundant. [ note 1 ] Other tabulations add, in addition to a unit for temperature, a unit for electric charge, so that either the Coulomb constant k e {\displaystyle k_{\text{e}}} [ 12 ] [ 13 ] [ 14 ] or the vacuum ...

  3. Brightness temperature - Wikipedia

    en.wikipedia.org/wiki/Brightness_temperature

    For a black body, Planck's law gives: [8] [11] = where (the Intensity or Brightness) is the amount of energy emitted per unit surface area per unit time per unit solid angle and in the frequency range between and +; is the temperature of the black body; is the Planck constant; is frequency; is the speed of light; and is the Boltzmann constant.

  4. Boltzmann constant - Wikipedia

    en.wikipedia.org/wiki/Boltzmann_constant

    Boltzmann constant: The Boltzmann constant, k, is one of seven fixed constants defining the International System of Units, the SI, with k = 1.380 649 x 10-23 J K-1.The Boltzmann constant is a proportionality constant between the quantities temperature (with unit kelvin) and energy (with unit joule).

  5. SI base unit - Wikipedia

    en.wikipedia.org/wiki/SI_base_unit

    kelvin: K thermodynamic temperature "The kelvin, symbol K, is the SI unit of thermodynamic temperature. It is defined by taking the fixed numerical value of the Boltzmann constant k to be 1.380 649 × 10 −23 when expressed in the unit J K −1, which is equal to kg m 2 s −2 K −1, where the kilogram, metre and second are defined in terms ...

  6. Second law of thermodynamics - Wikipedia

    en.wikipedia.org/wiki/Second_law_of_thermodynamics

    and the reference temperature T 1 * = 273.16 K × f(T 1,T 1) = 273.16 K. (Any reference temperature and any positive numerical value could be used – the choice here corresponds to the Kelvin scale.)

  7. Stefan–Boltzmann law - Wikipedia

    en.wikipedia.org/wiki/Stefan–Boltzmann_law

    The temperature Stefan obtained was a median value of previous ones, 1950 °C and the absolute thermodynamic one 2200 K. As 2.57 4 = 43.5, it follows from the law that the temperature of the Sun is 2.57 times greater than the temperature of the lamella, so Stefan got a value of 5430 °C or 5700 K. This was the first sensible value for the ...

  8. Temperature - Wikipedia

    en.wikipedia.org/wiki/Temperature

    Many scientific measurements use the Kelvin temperature scale (unit symbol: K), named in honor of the physicist who first defined it. It is an absolute scale. Its numerical zero point, 0 K, is at the absolute zero of temperature. Since May 2019, the kelvin has been defined through particle kinetic theory, and statistical

  9. Kelvin - Wikipedia

    en.wikipedia.org/wiki/Kelvin

    In 1967/1968, Resolution 3 of the 13th CGPM renamed the unit increment of thermodynamic temperature "kelvin", symbol K, replacing "degree Kelvin", symbol °K. [ 39 ] [ 40 ] [ 41 ] The 13th CGPM also held in Resolution 4 that "The kelvin, unit of thermodynamic temperature, is equal to the fraction ⁠ 1 / 273.16 ⁠ of the thermodynamic ...